1. Technical Field
A method of inhibiting patterns collapse by using a relacs (resist enhancement lithography assisted by chemical shrink) material is disclosed. More particularly, a method of forming photoresist patterns is disclosed that includes coating a relacs material on an underlying layer before coating photoresist material thereon and then heating the layer to inhibit pattern collapse.
2. Description of the Related Art
As semiconductor devices become more minute, thickness of photoresist to be coated becomes thinner. Due to the thinner thickness of photoresist, an underlying layer is not removed effectively during etching process. As a result, it is impossible to form a circuit.
A new etching process may be developed or a hard mask process may be additionally introduced to overcome the above problem. However, those processes cause the unit cost of production to increase and the pattern to have a higher aspect ratio (thickness of photoresist, height/linewidth of formed pattern), thereby resulting collapsing patterns.
After as photoresist patterns are formed using general lithography process, a process of cleaning semiconductor substrate is performed by spraying deionized water from a top portion of spin device with the semiconductor substrate spinning. During this process, high surface tension of deionized water results in pattern collapse.
In order to overcome the problem of pattern collapse, additives or surfactants may be added in the deionized water to decrease the surface tension of the deionized water.
Many attempts are made to improve adhesive force of photoresist on substrates, but obvious results have not been obtained therefrom.
Photoresist patterns collapse when the height of photoresist patterns goes beyond critical height and then the capillary force exceeds elasticity in photoresist (see FIG. 4).
Accordingly, there is a need to increase the elasticity of photoresist or decrease the surface tension of the photoresist result by increasing the adhesive force between the underlying layers and the photoresist, thereby preventing or reducing pattern collapse.
In satisfaction of the aforenoted need, a method for inhibiting photoresist pattern collapse using a relacs material is disclosed.